<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
<div class="moz-forward-container"><br>
<br>
-------- Original Message --------
<table class="moz-email-headers-table" border="0" cellpadding="0"
cellspacing="0">
<tbody>
<tr>
<th align="RIGHT" nowrap="nowrap" valign="BASELINE">Subject:
</th>
<td>Re: Lab</td>
</tr>
<tr>
<th align="RIGHT" nowrap="nowrap" valign="BASELINE">Date: </th>
<td>Sun, 26 Oct 2014 19:00:24 -0400</td>
</tr>
<tr>
<th align="RIGHT" nowrap="nowrap" valign="BASELINE">From: </th>
<td>Andrew J. Pounds <a class="moz-txt-link-rfc2396E" href="mailto:pounds_aj@mercer.edu"><pounds_aj@mercer.edu></a></td>
</tr>
<tr>
<th align="RIGHT" nowrap="nowrap" valign="BASELINE">Reply-To:
</th>
<td><a class="moz-txt-link-abbreviated" href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a></td>
</tr>
</tbody>
</table>
<br>
<br>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
<div class="moz-cite-prefix">The following reaction takes place in
<br>
<br>
HCl + NaOH -> NaCl + H2O<br>
<br>
The density of the NaCl solution is listed on the report form.<br>
<br>
<br>
On 10/26/14 18:56, wrote:<br>
</div>
<blockquote
cite="mid:C40B2F181831EF44A88CD73525827803130CFB7809@MERCERMAIL.MercerU.local"
type="cite">
<p dir="ltr">So for the mass of the solution for reaction three
do I need to know the density of HCl? It isn't listed in the
lab report form so can I just assume it's 1 g/mL?</p>
<div class="gmail_quote">On Oct 26, 2014 5:44 PM, "Andrew J.
Pounds" <<a moz-do-not-send="true"
href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>On 10/26/14 15:19, wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Hi Dr. Pounds!
<div>I'm trying to do the lab, and we either really
messed up in lab or I'm calculating the deltaH
values for reactions three and four wrong. I think
my mistake might be in calculating the mass of the
solution for these reactions. Could you give me any
pointers for calculating the mass of the solution
for reactions three and four?</div>
<div>Thanks! <br clear="all">
<div> <br>
</div>
</div>
</div>
</blockquote>
<br>
<font face="serif">So, in the equation <img
style="vertical-align:middle"
src="cid:part2.09030405.01050909@mercer.edu" alt="$q =
m c_s \Delta T$"> you need to use the mass of the
solution. You know the volume and the density of the
solution is listed on the lab report form. You can
therefore use <img style="vertical-align:middle"
src="cid:part3.06080009.07080703@mercer.edu" alt="$m =
\rho V$"> to compute the mass of the solutions. The
specific heats for these solutions can also be found on
the report form.<br>
<br>
Now, when it comes to <img
style="vertical-align:middle"
src="cid:part4.04090901.09040504@mercer.edu"
alt="$\Delta H$">, you have to remember that it is the
constant volume heat capacity on a per mole basis. So
take your <img style="vertical-align:middle"
src="cid:part5.03060507.03010804@mercer.edu" alt="$q$">
that you determined and divide it by the moles of
substance.<br>
<br>
In the case of the dissolution of NaOH you have roughly
2 grams of NaOH. Convert this to moles (2 g / 40
g/mol) = 0.05. So your enthalpy of reaction for the
dissolution of NaOH should be <img
style="vertical-align:middle"
src="cid:part6.07010100.09090006@mercer.edu" alt="$q /
0.05$">.<br>
<br>
In the case of the reaction of NaOH (aq) with HCl (aq)
you have 50 ml of 1 M NaOH (that would also be 0.05
moles), so divide the heat by that amount to get the
enthalpy like you did before.<br>
<br>
Hopefully that give you enought to get through the rest
of the lab, but let me know if you have any questions.<br>
<br>
<br>
<br>
<br>
</font><br>
<pre cols="72">--
Andrew J. Pounds, Ph.D. (<a moz-do-not-send="true" href="mailto:pounds_aj@mercer.edu" target="_blank">pounds_aj@mercer.edu</a>)
Professor of Chemistry and Computer Science
Mercer University, Macon, GA 31207 <a moz-do-not-send="true" href="tel:%28478%29%20301-5627" value="+14783015627" target="_blank">(478) 301-5627</a>
<a moz-do-not-send="true" href="http://faculty.mercer.edu/pounds_aj" target="_blank">http://faculty.mercer.edu/pounds_aj</a>
</pre>
</div>
</blockquote>
</div>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Andrew J. Pounds, Ph.D. (<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a>)
Professor of Chemistry and Computer Science
Mercer University, Macon, GA 31207 (478) 301-5627
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://faculty.mercer.edu/pounds_aj">http://faculty.mercer.edu/pounds_aj</a>
</pre>
<br>
</div>
<br>
</body>
</html>